import java.sql.*;
public class Example11_2 {
    public static void main(String args[]) {
        Connection con;
        Statement sql;
        ResultSet rs;
        con = GetDBConnection.connectDB("students","root","");
        if(con == null ) return;
        try {
            sql=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);
            rs = sql.executeQuery("SELECT * FROM mess ");
            rs.last();
            int max = rs.getRow();
            System.out.println("表共有"+max+"条记录,随机抽取2条记录：");
            int [] a =GetRandomNumber.getRandomNumber(max,2);//得到1-max之间2个不同随机数
            for(int i:a){
                rs.absolute(i);//油标移动到第i行
                String number = rs.getString(1);
                String name = rs.getString(2);
                Date date = rs.getDate(3);
                float h = rs.getFloat(4);
                System.out.printf("%s\t",number);
                System.out.printf("%s\t",name);
                System.out.printf("%s\t",date);
                System.out.printf("%.2f\n",h);
            }
            con.close();
        }
        catch(SQLException e) {
            System.out.println(e);
        }
    }
}

